1. Field of the Invention
This invention relates to an optical apparatus such as a photographic camera, a video camera or an SV camera, and particularly to an optical apparatus such as a photographic camera, a video camera or an SV camera having a function of forming an image of a photographer's eye looking into a finder through the finder, and extracting information relating to the photographer's eye on the basis of the image of the eye.
2. Related Background Art
There have heretofore been proposed various cameras in which a direction of a visual axis (a gazing direction) of a photographer is detected by a visual axis detecting device provided in the camera to thereby detect which area in a field of view of a finder the photographer is observing and various photographing functions such as automatic focus adjustment and automatic exposure adjustment are controlled on the basis of a signal from the visual axis detecting device.
For example, Japanese Laid-Open Patent Application No. 61-61135 proposes a camera designed such that the distance measuring direction of a focus detecting device is mechanically controlled on the basis of an output signal from the visual axis detecting device to thereby adjust a focus state of a phototaking optical system.
Japanese Laid-Open Patent Application No. 3-171122 proposes a camera having a visual axis detecting device designed such that infrared light from light source means provided in a portion of a finder optical system of a single-lens reflex camera is directed onto an optical axis of the finder optical system by the use of a dichroic mirror to thereby project the infrared light onto an eyeball of a photographer observing the field of view of the finder, and the infrared light reflected by a cornea of the eyeball is directed to an outside of a solid pentagonal prism through an eyepiece and an inclined reflecting surface of the solid pentagonal prism and is directed to a light receiving element of the visual axis detecting device.
A method of causing the reflected light from the photographer's eyeball to pass through the eyepiece, a light emergence surface of the solid pentagonal prism and an interior and the inclined reflecting surface thereof and emerge to the outside of the solid pentagonal prism, and thereafter directing it to the light receiving element and detecting it is characterized in that visual axis information can be obtained by a relatively simple construction. However, the method of directing the reflected light from the eyeball passed through the inclined reflecting surface (the final reflecting surface) of the solid pentagonal prism to a visual axis detecting system provided in the upper portion of the camera which is the opposite side to a photo-taking optical system mechanically interferes with a stroboscopic lamp contained in the portion above the solid pentagonal prism. Also, when in order to avoid the mechanical interference at this time, each element for visual axis detection is disposed in a certain degree of spaced apart relationship with the solid pentagonal prism, there arises the first problem that the portion around the solid pentagonal prism becomes bulky and, moreover, the entire camera becomes bulky.
Also, when an image of an eye is formed through the solid pentagonal prism, there has been a second problem that the variation of imaging magnification due to a positional change of the photographer's eye in a direction of an optical axis is not small, and in some cases, the visual axis (gazing) direction cannot be accurately detected.